Searching for Hidden Particles & getting rid of muons Oliver - - PowerPoint PPT Presentation

Searching for Hidden Particles & getting rid

• f muons

Oliver Lantwin

[oliver.lantwin@cern.ch]

ic student seminar 3rd November 2016

Hidden Particles Searching for Hidden Particles The catch: µs Conclusion

Oliver Lantwin (Imperial College London) ic student seminar 2/22

Hidden Particles Searching for Hidden Particles The catch: µs Conclusion

Oliver Lantwin (Imperial College London) ic student seminar Hidden Particles 2/22

State of the Standard Model

◮ Know there is new physics:

◮ Dark Matter ◮ Baryogenesis ◮ Neutrino masses

◮ Don’t know where: no indications yet for scale between ew and Planck ◮ We’d better look everywhere we can

◮ Strongly interacting: lhc, fcc? ◮ Super-weakly interacting: comet, lz, SHiP

Oliver Lantwin (Imperial College London) ic student seminar Hidden Particles 3/22

Dark Sector models L = Lsm + Lportal + Lds

Very general phenomenology:

◮ Something we know (sm), ◮ Something we think is there but don’t know (ds/new physics), ◮ Hopefully a portal other than gravity

• eg. dark matter mediator

Oliver Lantwin (Imperial College London) ic student seminar Hidden Particles 4/22

Many different portal models

◮ Scalar (e.g Higgs singlets) ◮ Fermions (e.g. heavy neutral leptons (hnl)) ◮ Vectors (e.g. dark photons)

Oliver Lantwin (Imperial College London) ic student seminar Hidden Particles 5/22

Hidden Particles Searching for Hidden Particles The catch: µs Conclusion

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 5/22

Searching for Hidden Particles

Clearly, if hidden particles: (A) can be created by colliding sm particles

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 6/22

Searching for Hidden Particles

Clearly, if hidden particles: (A) can be created by colliding sm particles ↔ (B) can decay back to sm

◮ So if we assume (A) we can look for visible decays back to the sm (B) ◮ If we assume ¬(A) hidden particles impossible to detect

But doesn’t have to be annihilation/pair-production

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 7/22

Searching for Hidden Particles

Clearly, if hidden particles: (A) can be created by colliding sm particles ↔ (B) can decay back to sm

◮ So if we assume (A) we can look for visible decays back to the sm (B) ◮ If we assume ¬(A) hidden particles impossible to detect

But doesn’t have to be annihilation/pair-production

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 7/22

Requirements

Problem: Guess what also decays visibly: sm particles

◮ need to reject sm processes

Portal processes need to be extremely rare, otherwise they would have been seen at general purpose experiments

◮ need extremely high intensity, no backgrounds

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 8/22

Requirements

Problem: Guess what also decays visibly: sm particles

◮ need to reject sm processes

Portal processes need to be extremely rare, otherwise they would have been seen at general purpose experiments

◮ need extremely high intensity, no backgrounds

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 8/22

Experimental sketch

High intensity: ⇒ fixed target, dense target No background: ⇒ need to filter out sm before they’re detected, doing it during data analysis impossible

◮ Focus on visible decays allows higher intensity and use of proton beam: We don’t

need to know the initial state!

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 9/22

Most of SHiP (ca. tp)

Evacuate vessel to get rid of neutrino interactions, add a hadron absorber...

2 × 1020 protons on target at 400 GeV

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 10/22

What can we do with SHiP?

See-saw hnl:

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 11/22

What can we do with SHiP?

Dark Photons:

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 12/22

What can we do with SHiP?

Light DM scattering:

Dark Matter (DM): prospects @ SHiP

SHiP 50 Events Relic Density LSND E137 BaBar K+++invisible Direct Detection

10-2 10-1 1 10-12 10-11 10-10 10-9 10-8 m(GeV) Y=2'(m/mV)4

• Courtesy ¡of ¡Patrick ¡

deNiverville ¡

Beyond ¡Collider ¡Physics, ¡CERN ¡ 8 ¡

MA’/Mχ=5 ¡ SHiP would be able to probe even beyond relic density in minimal hidden-photon model Background from neutrino interactions must be under control Requires dedicated study!

And a lot more!

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 13/22

SHiP (ca. tp)

But wait! We forgot the Muon sweeping magnets!

Oliver Lantwin (Imperial College London) ic student seminar Searching for Hidden Particles 14/22

Hidden Particles Searching for Hidden Particles The catch: µs Conclusion

Oliver Lantwin (Imperial College London) ic student seminar The catch: µs 14/22

The standard solution to muon background:

Put your experiment under a mountain against cosmic µs

Oliver Lantwin (Imperial College London) ic student seminar The catch: µs 15/22

The problem with that:

There is no mountain big enough for 1011 per spill, but if there were, there wouldn’t be any signal left anyway...

20 40 60 80 100 120 140

Distance of vessel from target (m)

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

A(N2,3 → µπ)

×10−4

1.6 GeV, 100000 events

Beauty+Cascade Charm+Cascade

Oliver Lantwin (Imperial College London) ic student seminar The catch: µs 16/22

Divert power to deflector shields

Now, something like this would be better: How do you deflect charged particles? Magnets!

Oliver Lantwin (Imperial College London) ic student seminar The catch: µs 17/22

Muon shield 101

One magnet won’t do, but two basically works:

Oliver Lantwin (Imperial College London) ic student seminar The catch: µs 18/22

More realistic muon shield

Z Z Y X Side view Top view

But still room for improvement...

Oliver Lantwin (Imperial College London) ic student seminar The catch: µs 19/22

Because it determines what space is available for physics!

20 40 60 80

Distance from target z[m]

2 4 6 8 10 12 14

|x| [m] Normalised µ occupancy for 5198390 µ

Envelope < 1E − 06 muons

10−6 10−5 10−4 10−3 10−2 10−1 20 40 60 80

Distance from target z[m]

2 4 6 8 10 12

|y| [m] Normalised µ occupancy for 5198390 µ

10−5 10−4 10−3 10−2 10−1 100

10 20 30 40 50 60 70 80

Distance from target z[m]

1 2 3 4 5 6

|x| , |y| [m] N → µµν acceptance envelope

x, 95% x, 99% x, 99.9% x, 100% y, 95% y, 99% y, 99.9% y, 100%

Oliver Lantwin (Imperial College London) ic student seminar The catch: µs 20/22

Because we can gain signal and save money with an optimised magnet

Before ⇒ after

20 40 60 80 100 120 140

Distance of vessel from target (m)

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

A(N2,3 → µπ)

×10−4

1.6 GeV, 100000 events

Beauty+Cascade Charm+Cascade

20 40 60 80 100 120 140

Distance of vessel from target (m)

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

A(N2,3 → µπ)

×10−4

1.6 GeV, 100000 events

Beauty+Cascade Charm+Cascade

+30% while saving 2500 t ≈ 7.5 Mchf

Oliver Lantwin (Imperial College London) ic student seminar The catch: µs 21/22

Hidden Particles Searching for Hidden Particles The catch: µs Conclusion

Oliver Lantwin (Imperial College London) ic student seminar Conclusion 21/22

Conclusion

◮ Searching for hidden particles is a way to study a very general phenomenology with

some very interesting models (including νmsm, ldm, R-parity violating susy)

◮ But it’s hard: need dedicated experiments ◮ SHiP is currently in the design phase

◮ tdr-but-don’t-call-it-that-for-political-reasons in 2018/19 ◮ will start running 2026

◮ This talk didn’t cover much of what I actually do...

@ First years: join us!

Oliver Lantwin (Imperial College London) ic student seminar Conclusion 22/22